Source : Webster's Revised Unabridged Dictionary (1913)

Proleg \Pro"leg\, n. [Pref. pro- for, in place of + leg.]
   (Zo["o]l.)
   One of the fleshy legs found on the abdominal segments of the
   larv[ae] of Lepidoptera, sawflies, and some other insects.
   Those of Lepidoptera have a circle of hooks. Called also
   {proped}, {propleg}, and {falseleg}.